CN112839745A - Method and device for controlling a stretch reducing mill for wall thickness compensation - Google Patents
Method and device for controlling a stretch reducing mill for wall thickness compensation Download PDFInfo
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- CN112839745A CN112839745A CN201980068166.8A CN201980068166A CN112839745A CN 112839745 A CN112839745 A CN 112839745A CN 201980068166 A CN201980068166 A CN 201980068166A CN 112839745 A CN112839745 A CN 112839745A
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- wall thickness
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B17/00—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling
- B21B17/02—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length
- B21B17/04—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length in a continuous process
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B17/00—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling
- B21B17/14—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling without mandrel, e.g. stretch-reducing mills
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/16—Control of thickness, width, diameter or other transverse dimensions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/78—Control of tube rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
- B21B38/04—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring thickness, width, diameter or other transverse dimensions of the product
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2261/00—Product parameters
- B21B2261/02—Transverse dimensions
- B21B2261/04—Thickness, gauge
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2275/00—Mill drive parameters
- B21B2275/02—Speed
- B21B2275/04—Roll speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/46—Roll speed or drive motor control
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Metal Rolling (AREA)
Abstract
A method and a control unit are described for controlling a stretch reducing mill for rolling tubes, which has a plurality of rolling stands (7) arranged one behind the other in the conveying direction of the tubes (6) to be rolled. A wall thickness measuring device (2-2, 9) determines a wall thickness profile (4) of a tube (6) to be rolled before rolling. A control unit (1, 1A, 1B) controls the respective rotational speed of the rolling stands (7) during the rolling of the tube on the basis of the determined wall thickness profile (4) in order to compensate for fluctuations in the wall thickness of the tube. It is proposed that a tube position measuring device (8) arranged upstream of the rolling stand (7) in the conveying direction continuously measures the current longitudinal coordinate (1x) of the tube (6), that measured values of the longitudinal coordinate (1x) of the tube (6) are transmitted to the control units (1A, 1B), and that the control units (1A, 1B) control the rotational speed of the rolling stand (7) during the rolling of the tube also on the basis of the transmitted measured values of the current longitudinal coordinate (1x) of the tube in order to compensate for fluctuations in the wall thickness of the tube. Furthermore, a tension reducing mill configured for carrying out the method is described.
Description
Technical Field
The present invention relates to a method for controlling a stretch reducing mill of the type according to independent claim 1. Furthermore, the invention relates to a control unit for a stretch reducing mill of the type according to independent claim 7. The invention also relates to a stretch reducing mill of the type according to independent claim 8.
Background
In the production of seamless tubes, a stretch-reducing rolling mill is used, which has a plurality of rolling stands arranged one behind the other in the direction of transport of the tube to be rolled. In order to achieve a reduction in the wall thickness of the tube, which necessarily occurs as a result of stretching or lengthening of the tube in the axial direction, the rolling speed of the rolling stand increases in the conveying direction.
The rolled stock exiting the tension reducing mill has fluctuations in wall thickness due to fluctuations in the wall thickness of the stock entering the tension reducing mill. Such fluctuations are caused, for example, by uneven rolling conditions, such as, for example, variations in the rolling temperature, uneven tool wear of the units arranged upstream of the stretch-reducing mill, etc. For this reason, the stretch-reducing mills can be equipped with control systems for controlling the wall thickness or reducing fluctuations in the wall thickness during the rolling of the tube.
A known technical solution for compensating for fluctuations in the wall thickness consists in influencing the elongation of the tube to be rolled by a targeted change of the respective rotational speed of the rolling stand. If, for example, sections of the tube which are introduced into the stretch-reducing rolling mill and have a wall thickness which is too large in relation to the desired value are rolled, the instantaneous elongation can be increased by a steeper speed curve, i.e. an increased speed difference between adjacent rolling stands, and the wall thickness can thereby be reduced to a greater extent. If, on the other hand, sections with a wall thickness that is too small compared to the nominal value are rolled, the instantaneous elongation can be reduced in the stretch-reducing rolling mill by a comparatively gentle speed profile. In this way, fluctuations in the wall thickness of the tube entering the stretch-reducing mill are compensated for, so that a homogenization of the wall thickness of the tube exiting the stretch-reducing mill and an improvement in the rolling quality are achieved.
The precondition for controlling the rotational speed of the rolling stand as a function of the wall thickness of the tube is that information about the wall thickness of the tube to be rolled and/or rolled is supplied to a control unit for the stretch reducing mill.
Document DE 2947233 a1 proposes an adjusting mechanism based on the measurement of the wall thickness of the tube to be rolled with an isotope radiometer before it enters the stretch-reducing mill, i.e. before it is deformed by the rolling stands of the stretch-reducing mill, the measurement of its speed before it enters the stretch-reducing mill, and the measurement of its speed after it exits the stretch-reducing mill. Such an adjustment mechanism suffers from the following disadvantages: short-wave wall thickness fluctuations with a stretch below the mill length cannot be adjusted.
Document US 3,496,745 a proposes that the control loop is dispensed with and that measurements for moderate wall thicknesses and wall thickness profiles of the tube to be rolled are carried out, i.e. only before the deformation by the rolling stand of the stretch reducing mill. In order to determine the wall thickness profile of the pipe to be rolled, the instantaneous wall thickness of the pipe to be rolled is measured at different longitudinal positions or ordinates of the pipe by means of a wall thickness measuring device and the measured wall thickness is stored as a wall thickness profile if assigned to a longitudinal position. During the rolling of the tube in the stretch-reducing mill, the control unit adjusts the respective rotational speeds of the rolling stands of the stretch-reducing mill according to a wall thickness control algorithm on the basis of a wall thickness profile determined in advance in a final manner by a wall thickness measuring device in order to compensate for fluctuations in the wall thickness of the tube to be rolled during the rolling of the tube in the stretch-reducing mill. Furthermore, document US 3,496,745 a proposes that the control unit starts the compensation for wall thickness fluctuations on the basis of the signals of an optical sensor arranged inside the stretch reducing mill or upstream of the first rolling stand of the stretch reducing mill and provided for detecting the end of the tube which is at the front in the direction of transport.
Generally, according to the disclosure of the document US 3,496,745 a, the wall thickness profile is determined not immediately upstream of the tube to be rolled in the rolling stand of the stretch-reducing mill, but rather far upstream of the stretch-reducing mill in terms of process engineering, for example, before the tube to be rolled is heated in a reheating furnace arranged upstream of the stretch-reducing mill. The wall thickness of the tube does not change during transport.
The optical sensor provided to detect the end of the front portion of the tube is exposed to steam, dust and splash water, which may result in inaccurate or erroneous detection results. If the end of the front section of the tube is detected only slightly too late due to the contamination of the optical sensor, the control unit initiates the control late for wall thickness compensation. In this case, the rotational speed change of the rolling stand, which is caused by the control unit, is carried out temporally after the actual position of the tube in the stretch-reducing mill, so that the wall thickness of the rolled tube may have any unpredictable fluctuations.
Another disadvantage of the prior art is that: the speed at which the tube is transported or fed into the stretch-reducing mill is not absolutely constant, but may vary during rolling. It is therefore not possible to determine precisely from the pure sensor signals for the front pipe end and the theoretical feed rate which section of the pipe is temporarily in the stretch-reducing mill.
Disclosure of Invention
The object of the present invention is therefore to provide a method and a control unit for controlling a stretch reducing mill, as well as a stretch reducing mill itself for rolling a tube, which method, control unit and stretch reducing mill ensure reliable compensation of fluctuations in the wall thickness of the tube to be rolled and of the wall thickness of the rolled tube within narrow tolerances.
The object of the invention is achieved by a method of the type described below having the features of claim 1. Advantageous embodiments of the method result from the features of the dependent claims 2 to 6. The object of the invention is also achieved by a control unit having the features of claim 7. The object of the invention is also achieved by a stretch reducing mill having the features of claim 8. Advantageous embodiments of the stretch-reducing mill result from the features of the dependent claims 9 to 13.
In order to solve the object of the invention, the inventors propose measuring the instantaneous position of the tube to be rolled relative to the first rolling stand of the stretch-reducing mill continuously by means of a tube position measuring device arranged upstream of the rolling stands in the direction of transport of the tube during the transport of the tube to be rolled to the rolling stands of the stretch-reducing mill. The measured values of the tube position measuring device are continuously transmitted to a control unit for the stretch reducing mill. The control unit controls the respective rotational speed of the rolling stands both on the basis of the wall thickness profile of the tube to be rolled determined by the wall thickness measuring device and on the basis of the continuously transmitted measured values of the tube position measuring device in order to compensate for fluctuations in the wall thickness of the tube to be rolled in the stretch-reducing rolling mill.
Specifically, according to the described method, the tube position measuring device measures the current longitudinal coordinate of the tube on a section of the tube that has not yet been rolled by the stretch-reducing mill. During the continuous measurement of the current ordinate of the tube to be rolled by the tube position measuring device, the tube is moved relative to the tube position measuring device in the conveying direction toward the stretch-reducing mill. The conveying direction corresponds to the longitudinal direction of the tube or to the direction of the ordinate of the tube. The tube position measuring device is designed to detect the position of the front end of the tube (also referred to as the tube tip) and the rear end of the tube (also referred to as the tube tail) in the conveying direction during this relative movement of the tubes and to assign the respective measured ordinates to these positions. The ordinate of the tube measured at one point in time represents the length of the section of the tube to be rolled which has passed the ordinate measurement carried out by the tube position measuring device. According to the method described, a length measurement is thereby carried out by the tube position measuring device, which length measurement is currently measured with a high temporal resolution, which longitudinal section or which tube length has already passed the tube position measuring device. The pipe position measuring device transmits the measured values determined by it continuously to the control unit or to an interface device which is designed for transmission to the control unit.
The tube position measuring device can determine the longitudinal coordinate of the tube by means of continuous measuring methods known per se for the tube length, such as, for example, optical, electromagnetic and/or imaging measuring methods. Whether the tube position measuring device measures the ordinate directly or indirectly by way of a mathematical modification of the initial measured variable, such as a single or multiple integration, is not essential to the invention.
The control unit calculates the longitudinal position of the tube, which is currently entering the stretch-reducing mill, i.e. currently coming into contact with the deformation rolls of the first rolling stand on the entry side, from the measurements of the longitudinal coordinate of the tube, which are continuously transmitted by the tube position measuring device. For this calculation, the control unit uses the distance known to it between the tube position measuring device and the first rolling stand on the entry side of the stretch-reducing mill. Furthermore, the control unit can calculate the total length of the pipe to be rolled from the measured ordinates of the two end portions of the pipe to be rolled.
The control unit determines the instantaneous or current wall thickness of the tube at its longitudinal position in the currently entering stretch-reducing mill from the previously determined wall thickness profile of the tube to be rolled, which is known to the control unit by means of the wall thickness measuring device. If this instantaneous wall thickness exceeds/falls below a predetermined nominal wall thickness, the control unit changes the rotational speed of the rolling stand according to the known rolling model in the sense of the steeper/gentler rotational speed profile explained above.
The control unit uses the current longitudinal position of the tube, which is determined as described above, in order to determine the instantaneous material distribution of the tube on the entry side, inside the stretch reducing mill and, if appropriate, also on the exit side of the stretch reducing mill, taking into account the known distance between the tube position measuring device and the first roll stand on the entry side of the stretch reducing mill, the distance between the roll stands of the stretch reducing mill, using a mathematical scheme for modeling the filling state inside the contact region between the tube and the rolls of the roll stand. In particular, the portion of the tube inside the stretch reducing mill is determined.
The term "continuous measurement of the ordinate of the tube" means that a plurality of measurements are carried out by the tube position measuring device during the relative movement between the tube position measuring device and the tube passing through the tube position measuring device, in order to measure how long a section of the tube which has passed through the tube position measuring device is at present. These measurements can be carried out continuously in time or discretely in time at defined times. The term "continuous measurement of the longitudinal coordinate of the tube" is not to be understood to mean that only the tube tip of the tube to be rolled is detected and the detection result is reported to the control unit.
Since in the proposed method the current position of the tube upstream and in the tension reducing mill is determined with high precision and is supplied separately to the control unit as a complement to the determined wall thickness profile, the control unit can precisely control the respective rotational speed of the rolling stands in order to compensate for fluctuations in the wall thickness of the tube inserted into the tension reducing mill, so that the rolled tube has only small wall thickness fluctuations within narrow tolerances.
In addition, a stretch-reducing mill for rolling a pipe in the sense of the invention is described, which, in correspondence with the described method, makes it possible to achieve the same advantages as those achieved with the described method. The stretch-reducing rolling mill has a plurality of rolling stands arranged one after the other in the direction of transport of the tube to be rolled. The tension reducing mill is furthermore coupled to or provided with a wall thickness measuring device arranged upstream of the rolling stand in the conveying direction for determining a wall thickness profile of the tube to be rolled, and a control unit for controlling the respective rotational speed of the rolling stand during the rolling of the tube on the basis of the determined wall thickness profile in order to compensate for fluctuations in the wall thickness of the tube. The stretch-reducing rolling mill is also coupled to or provided with a tube position measuring device arranged upstream of the rolling stand in the conveying direction, for continuously measuring the current vertical coordinate of the tube and for transmitting the measured values of the current vertical coordinate of the tube to the control unit. Furthermore, the control unit is designed to control the rotational speed of the rolling stand during the rolling of the tube also on the basis of the received measured values of the current ordinate of the tube in order to compensate for fluctuations in the wall thickness of the tube.
Furthermore, according to the invention, a control unit for a stretch reducing mill is described. The control unit is designed to control the respective rotational speed of the rolling stands on the basis of a wall thickness profile of the tube to be rolled, which is determined by the wall thickness measuring device prior to rolling. Furthermore, the control unit is configured to receive measured values of the current vertical coordinate of the tube, which are measured continuously by a tube position measuring device arranged upstream of the rolling stand in the conveying direction. Furthermore, the control unit is designed to control the rotational speed of the rolling stand during the rolling of the tube also on the basis of the received measured values of the current ordinate of the tube in order to compensate for fluctuations in the wall thickness of the tube.
The features of the invention described above which are based on the method should also be suitable for the device described above, i.e. the control unit and the stretch-reducing mill, and can be claimed and vice versa. Furthermore, the invention encompasses any combination of the improvements and improvements described herein.
In a further development of the method described, it is provided that the control unit controls the rolling of a first section of the tube, in particular the respective rotational speed of the rolling stands, on the basis of the measured values of the longitudinal coordinate of the tube, while the tube position measuring device continuously measures the current longitudinal coordinate of the tube on a second section of the tube.
A further development of the described stretch-reducing rolling mill corresponds to the development of the method, for which the conveying path of the tube to be rolled from the tube position measuring device of the stretch-reducing rolling mill to the first rolling stand in the conveying direction is shorter than the total length of the tube to be rolled. In a development of this development, the delivery path is shorter than half the total length of the tube to be rolled. In a further development of this development, the delivery path is shorter than a quarter of the total length of the tube to be rolled.
The longitudinal coordinate of the tube is measured on the rear section of the tube and at the same time the rotational speed of the rolling stand is controlled during the rolling of the front section of the tube on the basis of the already existing measured values of the longitudinal coordinate, in such a way that the control unit obtains the current position of the tube particularly precisely and therefore the rotational speed of the rolling stand can be adapted to the current wall thickness known from the determined wall thickness profile for the control unit particularly precisely at the current position. A particularly high compensation for fluctuations in the wall thickness of the incoming pipe is thus achieved. The shorter the transport distance or spacing between the tube position measuring device and the first rolling stand into which the tube to be rolled enters, the higher the accuracy of the compensation for fluctuations in the wall thickness of the tube to be rolled.
In a further development of the method described, it is provided that the control unit controls the rolling of a first section of the tube, in particular the respective rotational speed of the rolling stands, and that the wall thickness measuring device determines a wall thickness profile over a second section of the tube.
A development of the described stretch-reducing rolling mill, for which the conveying path of the tube to be rolled from the wall thickness measuring device of the stretch-reducing rolling mill to the first rolling stand in the conveying direction is shorter than the total length of the tube to be rolled, corresponds to this development of the described method.
In one development of this development, the conveying path or distance from the wall thickness measuring device to the first rolling stand is shorter than half the total length of the tube to be rolled. In a further development of this development, the delivery path is shorter than a quarter of the total length of the tube to be rolled.
The wall thickness profile of the tube is determined on the rear section of the tube and at the same time the rotational speed of the rolling stand is controlled during the rolling of the front section of the tube on the basis of the already existing measured values of the ordinate and the partially determined wall thickness profile, in such a way that the control unit obtains the current position of the tube particularly precisely and the rotational speed of the rolling stand can therefore be matched particularly precisely at the current position to the current wall thickness known from the partially determined wall thickness profile for the control unit. A particularly precise compensation for fluctuations in the wall thickness of the incoming pipe is thus achieved. The shorter the transport path or distance between the wall thickness measuring device and the first rolling stand into which the tube to be rolled enters, the higher the accuracy of the compensation for fluctuations in the wall thickness of the tube to be rolled.
In accordance with a further development of the method described, it is provided that the measured values of the longitudinal axis of the tube, which are measured by the tube position measuring device, are used to determine the wall thickness profile and are transmitted to the control unit. The wall thickness measured by the wall thickness measuring device is therefore linked to the value of the longitudinal coordinate of the tube measured by the tube position measuring device, which value is also transmitted to the control unit. The wall thickness of the tube to be rolled is preferably measured at the longitudinal position of the tube to be rolled which is currently measured by the tube position measuring device as the current ordinate.
A development of the described stretch-reducing rolling mill, for which the tube position measuring device and the wall thickness measuring device are designed to measure simultaneously the same tube to be rolled, corresponds to this development of the method. In one development of this development, the tube position measuring device and the wall thickness measuring device are designed as a single integrated device which measures the current ordinate of the tube to be rolled and the wall thickness present at this position or ordinate, combines these measured values into a wall thickness profile, and transmits the measured values of the wall thickness profile and the ordinate to the control unit.
In a particularly preferred embodiment, the wall thickness measuring device and the tube position measuring device of the described stretch reducing mill are integrated in a single measuring device, which is arranged such that a section of the tube to be rolled is measured with respect to the wall thickness and the ordinate, and the section of the tube which has been measured is rolled under the control of the control unit on the basis of the measured wall thickness and the ordinate in order to compensate for fluctuations in the wall thickness of the tube to be rolled.
With these improvements, a particularly precise assignment between the measured wall thickness and the measured ordinate is determined, which leads to a particularly precise compensation for fluctuations in the wall thickness under the control of the control unit.
According to a further development of the method described, the tube position measuring device measures the ordinate of the tube only when the wall thickness measuring device has determined a wall thickness profile over the entire length of the tube to be rolled, the measured value of the ordinate being intended to be transmitted to the control unit.
A further development of the described stretch-reducing rolling mill corresponds to the development of the method, in which the conveying path of the tube to be rolled between the wall thickness measuring device and the tube position measuring device or the first rolling stand is greater than the total length of the tube to be rolled.
These improvements provide the following advantages: in the case of conventional existing stretch-reducing mills, in which the distance between the wall thickness measuring device and the first rolling stand into which the tube to be rolled first enters is significantly greater than the overall length of the tube to be rolled, the conventional existing stretch-reducing rolling mill can easily be improved in the sense of the present invention by: the tube position measuring device described above is inserted between the wall thickness measuring device and the first rolling stand at a small distance relative to the first rolling stand.
According to a further development of the method described, the control unit also controls the rotational speed of the rolling stand on the basis of signals from sensors arranged inside the stretch-reducing mill and/or downstream of the stretch-reducing mill in the direction of transport of the tube in order to compensate for fluctuations in the wall thickness of the tube during rolling. The accuracy of the method and its reliability are further increased by additional sensors, in particular when rolling short tubes. Then, that is to say possibly the parent tube has left the tube position measuring device, while the front tube end has not left the stretch reducing mill. By means of an additional sensor, the actual feed of the tube can be detected and can be taken into account by the control mechanism.
A development of the described stretch-reducing mill, which is coupled to or provided with sensors at or between the rolling stands and/or downstream of the stretch-reducing mill in the direction of transport of the tube, corresponds to this development of the method. The sensor is preferably designed as a proximity sensor in order to detect as precisely as possible the current position of the tube in the region of the rolling stand and/or after exiting the last rolling stand. The control unit is then configured to control the rotational speed of the rolling stand, also on the basis of the signals of the sensors, in order to compensate for fluctuations in the wall thickness of the tube during rolling.
Drawings
For the purpose of illustrating the proposed method and the proposed stretch reducing mill, embodiments of the invention will now be described with reference to the following drawings.
Fig. 1 schematically illustrates a stretch reducing mill with a wall thickness measuring device and a proximity sensor upstream of the rolling stand, which represents the basis for the embodiment shown in fig. 2 and 3 from the point of view of the inventors;
FIG. 2 schematically illustrates an embodiment of a stretch reducing mill having a wall thickness measurement device upstream of the rolling stand and a separate tube position measurement device;
FIG. 3 schematically illustrates an embodiment of a stretch reducing mill having integrated wall thickness and tube position measuring devices upstream of the rolling stands;
in the drawings, the same or similar components are denoted by the same reference numerals throughout the drawings.
Detailed Description
To better illustrate the embodiments, a stretch reducing mill with a wall thickness measuring device and proximity sensors upstream of the rolling stand is first described with reference to fig. 1, which represents the basis of the embodiments illustrated in fig. 2 and 3 for the present invention from the point of view of the inventors.
The flow of tube measurement (see phase a) and tube rolling (see phase B) is schematically shown in fig. 1. In a phase a, which is clearly prior in time to the tube to be rolled being moved into the rolling stand, the tube 6 to be rolled is guided in its longitudinal direction through the wall thickness measuring device 2-2, which measures the current wall thickness s of the tube 6 during the tube movement in a radio-electric manner and transmits it to the evaluation unit 3. Together with the measurement of the current wall thickness s, the current ordinate ix of the tube 6 is measured in the tube position measuring device 2-1 during the passage of the tube 6 through the wall thickness measuring device 2-2. The measurement of the current ordinate ix can be performed optically, for example, as shown in fig. 1. The evaluation unit 3 assigns the measured current wall thickness s of the tube 6 to be rolled and the measured current longitudinal position lx, at which the wall thickness measurement is carried out, to each other and thus determines the wall thickness profile 4 of the tube 6 to be rolled. Furthermore, the evaluation unit 3 determines the total pipe length lges of the pipe 6 to be rolled from the measured current ordinate of the front and rear pipe ends.
The determined wall thickness profile 4 and the determined manifold length lges are transmitted from the evaluation unit to the control unit 1 for the stretch-reducing rolling mill. The measurement explained in relation to fig. 1 for the current ordinate ix of the tube 6 is used only for determining the wall thickness profile 4, and the measured values of the current ordinate ix are not transmitted individually to the control unit 1. The control unit 1 is designed to control the respective rotational speed of the rolling stand 7 or of the working rolls thereof on the basis of the wall thickness profile 4 determined and transmitted by the evaluation unit 3. After the wall thickness profile 4 has been determined, the tube 6 to be rolled is fed to a reheating furnace (not shown) and subsequently to the rolling stand 7 of the stretch-reducing mill as illustrated in fig. 1 as phase B for the same tube 6. In order to detect the arrival of the tube 6 to be rolled at the stretch-reducing mill, a proximity sensor 5, which is embodied as a photocell, is arranged upstream of the rolling stand 7 of the stretch-reducing mill at a distance a. The proximity sensor 5 detects the arrival of the tube tip of the tube 6 to be rolled and reports the detection time t0 to the control unit 1, whereupon the control unit 1 continuously measures the time t since this time t 0. The spacing a between the proximity sensor 5 and the first rolling stand 7-1 is known to the control unit 1. The approach speed v of the tube 6 towards the first rolling stand 7-1 is also known to the control unit 1. The approach speed v can be a predetermined value or can be derived during operation, for example from the rotational speed of the roller conveyor motor.
In order to control the rotational speed of the rolling stand 7 during the passage of the tube through the rolling stand 7, the control unit 1 requires current position information, namely: which position or longitudinal position of the tube to be rolled is currently reached at the first rolling stand 7-1. With this current position information, the control unit 1 determines from the previously determined wall thickness profile 4 of the tube 6 to be rolled, which at the current entry into the first rolling stand 7-1 has a wall thickness s that deviates from the nominal wall thickness, which necessitates a change in the rotational speed of the rolling stand. The control unit 1 determines the necessary rotational speed change by means of an algorithm known per se, the degree of which depends on the magnitude of the wall thickness deviation. The control unit functions as:
lx＝lges+a-v·(t-t0)
to determine the position or ordinate ix of the tube currently moved into the first rolling stand 7-1. The calculation criterion provides a position value for lx in the limit 0 ≦ lx ≦ lges.
In the control illustrated in fig. 1, which is carried out for the purpose of compensating for fluctuations in the wall thickness of the tube to be rolled, the longitudinal coordinate lx currently being moved into the first rolling stand 7-1 is determined indirectly, i.e. by measuring the time t from the instant t0 determined by the proximity sensor 5 and by using the approach speed v of the tube 6.
An embodiment of the proposed stretch reducing mill resulting from a modification of the structure illustrated in fig. 1 is illustrated in fig. 2. The determination of the wall thickness profile 4 is carried out in the exemplary embodiment illustrated in fig. 2 as already explained with reference to fig. 1, so that a renewed explanation is dispensed with. In the exemplary embodiment illustrated in fig. 2, however, instead of the proximity sensor 5 illustrated in fig. 1 for detecting the tube tip, a tube position measuring device 8 is provided which continuously and with high time resolution measures the current ordinate ix of the tube 6 or the tube length ix 1 which has already passed the tube position measuring device 8. The tube position measuring device 8 is arranged upstream of the first roll stand 7-1 of the stretch-reducing mill at a distance a and continuously measures the current ordinate lx of the tube. The measured values of the tube position measuring device 8 are continuously transmitted to the control unit 1A. The control unit 1A functions as:
lx＝lges-lx1+a
to determine the position or vertical coordinate of the tube 6 currently moved into the rolling stand 7-1.
This way of directly determining the longitudinal position of the tube 6 currently moved into the first rolling stand 7-1 provides the advantage that the accuracy of the position determination of the tube is higher than in the configuration illustrated in fig. 1. Since the position of the tube moved into the first rolling stand 7-1 can be determined very precisely in accordance with the exemplary embodiment of fig. 2, the control unit 1A can determine the current wall thickness s of the tube very precisely at this position from the determined wall thickness profile 4 and can therefore also control the rotational speed of the rolling stand 7 very precisely on the basis of the determined current wall thickness.
The main difference between the tension reducing mills with upstream measuring devices illustrated in fig. 1 and 2 is that in the exemplary embodiment illustrated in fig. 2, the measured values of the current longitudinal position of the tube to be rolled are continuously transmitted to the control unit 1A, and the control unit 1A also controls the rotational speed of the rolling stand on the basis of these measured values in order to compensate for fluctuations in the wall thickness of the tube to be rolled.
Furthermore, the embodiment according to fig. 2 provides a particularly large capability for compensating for fluctuations in the wall thickness of the tube to be rolled, if the tube position measuring device 8 measures the current ordinate of the rear section of the tube, while the control unit 1A simultaneously controls the rotational speed of the rolling stand 7 during the rolling of the front section of the tube. In this case, the delivery travel of the tube from the tube position measuring device 8 of the stretch-reducing mill to the first rolling stand 7-1 is shorter than the total length lges of the tube 6 to be rolled.
The exemplary embodiment illustrated in fig. 2 is preferably used if a stretch reducing mill with an already existing wall thickness measuring device, which measures the tube to be rolled relatively far before it is moved into the rolling stand, is to be improved in the direction of accuracy of the compensation for wall thickness fluctuations.
Fig. 3 illustrates a further embodiment of the proposed stretch-reducing mill, wherein, in contrast to the embodiment of fig. 2, the wall thickness measuring device 9 is arranged in the immediate vicinity upstream of the first rolling stand 7-1 of the stretch-reducing mill. The transport path of the tube to be rolled from the wall thickness measuring device 9 to the first rolling stand 7-1 is shorter than the total length lges of the tube to be rolled 6. The tube is preferably both in the wall thickness measuring device 9 and in the rolling stand 7 of the stretch-reducing mill during the major part of the rolling time. The tube position measuring device 8 is preferably designed as an integrated device 10 together with the wall thickness measuring device 9, so that the tube position measuring device 8 and the wall thickness measuring device 10 measure the tube 6 simultaneously.
As shown in fig. 3, the measured values of the tube position measuring device 8 are doubled and simultaneously fed to the evaluation unit 3 for determining the wall thickness profile 4 and to the control unit 1B for controlling the rotational speed of the rolling stand. During the continuous measurement of the ordinate ix by the tube position measuring device 8 and the continuous transmission of the corresponding data stream to the control unit 1B, the evaluation unit 3 continuously transmits a data stream to the control unit 1B, which data stream represents the determined wall thickness profile 4 of the measured tube section. As already explained with reference to fig. 2, the control unit 1B determines, taking into account the known distance a of the integrated device 10 of the tube position and wall thickness measuring device from the first rolling stand 7-1, which tube position or tube coordinate is currently entering the first rolling stand and which tube section has already been moved into the rolling stand 7, from the measured ordinate of the tube currently transmitted by the tube position measuring device. At the same time, the control unit 1B determines the current wall thickness at the tube position currently entering the first rolling stand 7-1 from the data stream of the wall thickness profile 4 and calculates the possibly necessary rotational speed correction on the basis of these data in order to correct for fluctuations in the wall thickness of the tube to be rolled during rolling.
The exemplary embodiment illustrated in fig. 3 provides a particularly great degree of accuracy in the compensation of fluctuations in the wall thickness of the tube to be rolled, since the current wall thickness and the current longitudinal coordinate of the tube are measured at a small distance from the first rolling stand while the front section of the tube is being rolled.
List of reference numerals:
1. 1A, 1B control unit
2-1 pipe position measuring device
2-2 wall thickness measuring device
3 analysis Unit
4 wall thickness profile determined
5 proximity sensor
6 pipe
7 Rolling stand
7-1 first Rolling Mill Stand
8 pipe position measuring device
9 wall thickness measuring device
10 integrated measuring device
a proximity sensor or tube position measuring device and the first rolling stand
Of (2) is
Total length of lges tube
lx ordinate
lx1 tube length that has been measured by the tube position measuring device
Wall thickness of s-tube
t0 time of tube tip detection
t current time
v closing velocity of tube
Claims (13)
1. Method for controlling a stretch reducing mill for rolling a tube, the stretch reducing mill having a plurality of rolling stands (7) arranged one after the other in the conveying direction of the tube (6) to be rolled, wherein wall thickness measuring devices (2-2, 9) determine a wall thickness profile (4) of the tube (6) to be rolled before rolling, and a control unit (1, 1A, 1B) controls the respective rotational speed of the rolling stands (7) during the rolling of the tube on the basis of the determined wall thickness profile (4) in order to compensate for fluctuations in the wall thickness of the tube, characterized in that a tube position measuring device (8) arranged upstream of the rolling stands (7) in the conveying direction continuously measures the current longitudinal coordinate (1x) of the tube (6), the measured value of the longitudinal coordinate (1x) of the tube (6) being transmitted to the control unit (1A, to, 1B) And the control unit (1A, 1B) controls the rotational speed of the rolling stand (7) during rolling of the tube also on the basis of the transmitted measurement values of the current ordinate (1x) of the tube in order to compensate for fluctuations in the wall thickness of the tube.
2. Method according to claim 1, characterized in that the control unit (1A, 1B) controls the rolling of a first section of the tube on the basis of the measured values of the longitudinal coordinate (1x) of the tube during the continuous measurement of the current longitudinal coordinate (1x) of the tube on a second section of the tube by the tube position measuring device (8).
3. Method according to claim 1 or 2, characterized in that the control unit (1B) controls the rolling of a first section of the tube during the continuous measurement of the wall thickness variation curve (4) by the wall thickness measuring device (8) on a second section of the tube.
4. Method according to one of claims 1 to 3, characterized in that the measured values of the tube ordinate (lx) measured by a tube position measuring device (8) are used for determining the wall thickness profile (4) and for transmitting them to the control unit (1B).
5. Method according to claim 1 or 2, characterized in that the tube position measuring device (8) measures the ordinate (lx) of the tube only if the wall thickness measuring device (2-2) has determined the wall thickness variation curve within the range of the total length (lges) of the tube (6) to be rolled.
6. A method according to any one of claims 1 to 5, characterised in that the control unit (1A, 1B) also controls the rotational speed of the rolling stand (7) on the basis of the signals of sensors arranged inside the stretch reducing mill and/or downstream of the stretch reducing mill in the transport direction of the tube in order to compensate for fluctuations in the wall thickness of the tube during rolling.
7. A control unit (1A, 1B) for a stretch reducing mill for rolling tubes, having a plurality of rolling stands (7) arranged one after the other in the conveying direction of a tube (6) to be rolled, wherein the control unit (1A, 1B) is configured for controlling the respective rotational speed of the rolling stands (7) on the basis of a wall thickness variation curve (4) of the tube to be rolled, which is determined before rolling by means of a wall thickness measuring device (2-2, 9), in order to compensate for fluctuations in the wall thickness of the tube, characterized in that the control unit (1A, 1B) is furthermore configured for receiving measured values of a current longitudinal coordinate (1x) of the tube (6), which are measured continuously by means of a tube position measuring device (8) arranged upstream of the rolling stands (7) in the conveying direction, and the control unit (1A, 1B) is furthermore configured to control the rotational speed of the rolling stand (7) during rolling of the tube also on the basis of the received measurement values of the current ordinate (lx) of the tube in order to compensate for wall thickness fluctuations of the tube.
8. A tension reducing mill for rolling tubes, having a plurality of rolling stands (7) arranged one after the other in the conveying direction of the tubes to be rolled, which are coupled to or provided with wall thickness measuring devices (2-2, 9) arranged upstream of the rolling stands in the conveying direction for determining a wall thickness profile (4) of the tubes (6) to be rolled, and a control unit (1, 1A, 1B) for controlling the respective rotational speed of the rolling stands (7) during the rolling of the tubes on the basis of the determined wall thickness profile (4) in order to compensate for fluctuations in the wall thickness of the tubes, characterized in that the tension reducing mill is furthermore coupled to a tube position measuring device (8) arranged upstream of the rolling stands (7) in the conveying direction Coupled to or provided with the position measuring device for continuously measuring the current ordinate (lx) of the tube and for transmitting the measured values of the current ordinate (lx) of the tube to the control unit (1A, 1B), and the control unit (1A, 1B) is furthermore configured for controlling the rotational speed of the rolling stand (7) during the rolling of the tube also on the basis of the received measured values of the current ordinate (lx) of the tube in order to compensate for fluctuations in the wall thickness of the tube.
9. A stretch-reducing mill according to claim 8, characterized in that the delivery travel of the tube (6) to be rolled from its tube position measuring device (8) to the first rolling stand (7-1) of the stretch-reducing mill in the delivery direction is shorter than the total length (lges) of the tube (6) to be rolled, preferably half the total length, particularly preferably a quarter of the total length.
10. A stretch-reducing mill according to claim 8 or 9, characterized in that the transport path of the tube (6) to be rolled from the wall thickness measuring device (9) of the stretch-reducing mill to the first rolling stand (7-1) of the stretch-reducing mill in the transport direction is shorter than the total length (lges) of the tube (6) to be rolled, preferably half the total length, particularly preferably a quarter of the total length.
11. A stretch reducing mill according to any one of claims 8 to 10, characterized in that the tube position measuring device (8) and the wall thickness measuring device (9) are configured for measuring the same tube (6) to be rolled simultaneously and preferably as one integrated apparatus (10).
12. A stretch-reducing mill according to claim 8 or 9, characterized in that the delivery travel of the tube to be rolled between the wall thickness measuring device (2-2) and the tube position measuring device (8) is longer than the total length (lges) of the tube to be rolled (6).
13. A stretch reducing mill according to any one of claims 8 to 11, characterized in that the stretch reducing mill is coupled to or provided with sensors arranged inside the stretch reducing mill and/or downstream of the stretch reducing mill in the conveying direction of the tube, and that the control unit (1A, 1B) is configured to control the rotational speed of the rolling stand (7) also on the basis of the signals of the sensors in order to compensate for fluctuations in the wall thickness of the tube during rolling.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102018214002.2A DE102018214002A1 (en) | 2018-08-20 | 2018-08-20 | Method and device for controlling a stretch-reducing mill for wall thickness compensation |
| DE102018214002.2 | 2018-08-20 | ||
| PCT/EP2019/071975 WO2020038832A1 (en) | 2018-08-20 | 2019-08-15 | Method and device for controlling a stretch reducing rolling mill for wall thickness compensation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112839745A true CN112839745A (en) | 2021-05-25 |
| CN112839745B CN112839745B (en) | 2023-07-14 |
Family
ID=67660568
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201980068166.8A Active CN112839745B (en) | 2018-08-20 | 2019-08-15 | Method and device for controlling a tension reducing mill for wall thickness compensation |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US11745235B2 (en) |
| EP (1) | EP3840896B1 (en) |
| CN (1) | CN112839745B (en) |
| DE (1) | DE102018214002A1 (en) |
| ES (1) | ES2935312T3 (en) |
| MA (1) | MA53425A (en) |
| MX (1) | MX2021001918A (en) |
| PL (1) | PL3840896T3 (en) |
| RU (1) | RU2758745C1 (en) |
| SI (1) | SI3840896T1 (en) |
| WO (1) | WO2020038832A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114001683A (en) * | 2021-10-26 | 2022-02-01 | 大连理工大学 | Complex component machining residual wall thickness self-adaptive compensation method based on coordinate origin translation |
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| DE3437449A1 (en) * | 1984-10-12 | 1986-04-17 | Betriebsforschungsinstitut VDEh - Institut für angewandte Forschung GmbH, 4000 Düsseldorf | Device for detecting thickness fluctuations in cold-rolled metal sheets |
| CN1470338A (en) * | 2002-07-03 | 2004-01-28 | SMS�����ɷݹ�˾ | Method and apparatus for measuring eccentricity of hollow tube blank |
| CN1496766A (en) * | 2002-09-25 | 2004-05-19 | Sms米尔股份有限公司 | Method and device for measuring wall thickness of pipe in pipe mill |
| CN102873100A (en) * | 2011-07-13 | 2013-01-16 | 中冶东方工程技术有限公司 | Three-roller full-floating mandrel continuous pipe rolling mill and rolling process thereof |
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| US3496745A (en) * | 1967-05-01 | 1970-02-24 | Kocks Gmbh Friedrich | Process for stretch-reducing tubes |
| JPS5325259A (en) | 1976-08-20 | 1978-03-08 | Sumitomo Metal Ind | Metal pipe outer diameter control device |
| SU812366A1 (en) * | 1979-02-21 | 1981-03-15 | Предприятие П/Я В-8173 | Apparatus for monitoring tube wall width difference |
| SU856602A1 (en) * | 1979-08-02 | 1981-08-23 | Уральский научно-исследовательский институт трубной промышленности | Apparatus for monitoring tube wall mean thickness |
| DE2947233C2 (en) * | 1979-11-23 | 1992-03-12 | Kocks Technik Gmbh & Co, 4010 Hilden | Device for controlling the wall thickness of pipes |
| CA2519093C (en) * | 2003-03-14 | 2009-04-28 | Sumitomo Metal Industries, Ltd. | Method and apparatus for producing pipe, wall thickness variation-obtaining device, and computer program |
| DE602005024782D1 (en) * | 2004-03-30 | 2010-12-30 | Sumitomo Metal Ind | METHOD AND DEVICE FOR CONTROLLING THE ROLLING OF TUBES WITH FIXED DIAMETER |
| DE102015118065A1 (en) * | 2015-10-22 | 2017-04-27 | Hans Joachim Pehle | Method for adjusting the speed of continuous tube rolling mills |
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2018
- 2018-08-20 DE DE102018214002.2A patent/DE102018214002A1/en active Pending
-
2019
- 2019-08-15 RU RU2021103229A patent/RU2758745C1/en active
- 2019-08-15 US US17/270,022 patent/US11745235B2/en active Active
- 2019-08-15 ES ES19755610T patent/ES2935312T3/en active Active
- 2019-08-15 PL PL19755610.3T patent/PL3840896T3/en unknown
- 2019-08-15 WO PCT/EP2019/071975 patent/WO2020038832A1/en active Application Filing
- 2019-08-15 MX MX2021001918A patent/MX2021001918A/en unknown
- 2019-08-15 EP EP19755610.3A patent/EP3840896B1/en active Active
- 2019-08-15 CN CN201980068166.8A patent/CN112839745B/en active Active
- 2019-08-15 SI SI201930423T patent/SI3840896T1/en unknown
- 2019-08-15 MA MA053425A patent/MA53425A/en unknown
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US3401547A (en) * | 1966-01-26 | 1968-09-17 | Gen Dynamics Corp | Measurement and control of rolled material thickness and quality |
| DE3437449A1 (en) * | 1984-10-12 | 1986-04-17 | Betriebsforschungsinstitut VDEh - Institut für angewandte Forschung GmbH, 4000 Düsseldorf | Device for detecting thickness fluctuations in cold-rolled metal sheets |
| CN1470338A (en) * | 2002-07-03 | 2004-01-28 | SMS�����ɷݹ�˾ | Method and apparatus for measuring eccentricity of hollow tube blank |
| CN1496766A (en) * | 2002-09-25 | 2004-05-19 | Sms米尔股份有限公司 | Method and device for measuring wall thickness of pipe in pipe mill |
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| CN114001683A (en) * | 2021-10-26 | 2022-02-01 | 大连理工大学 | Complex component machining residual wall thickness self-adaptive compensation method based on coordinate origin translation |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112839745B (en) | 2023-07-14 |
| MX2021001918A (en) | 2021-04-28 |
| RU2758745C1 (en) | 2021-11-01 |
| EP3840896B1 (en) | 2022-10-12 |
| US20210323039A1 (en) | 2021-10-21 |
| EP3840896A1 (en) | 2021-06-30 |
| ES2935312T3 (en) | 2023-03-03 |
| WO2020038832A1 (en) | 2020-02-27 |
| PL3840896T3 (en) | 2023-01-23 |
| US11745235B2 (en) | 2023-09-05 |
| DE102018214002A1 (en) | 2020-02-20 |
| MA53425A (en) | 2022-05-11 |
| SI3840896T1 (en) | 2023-02-28 |
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